Cements and cement composites are useful as structural materials for a variety of applications where settable materials with high compressive strength are desired. In some instances, a number of additives may be combined with cement that change various properties such as increasing flexural and tensile strength, modifying the setting time, or changing the rheological properties of a cement slurry prior to application.
In oilfield applications, cementing operations are often conducted after drilling of a wellbore has been completed. During completions operations, for example, a wellbore may be cased with a number of lengths of pipe prior to injection of a cement slurry. After placement of casing, the casing may be secured to the surrounding earth formations during primary cementing operations by pumping a cement slurry into an annulus between the casing and the surrounding formations that then hardens to retain the casing in position. The cement composition may then be allowed to solidify in the annular space, thereby forming a sheath of cement that prevents the migration of fluid between zones or formations previously penetrated by the wellbore.